Counterbalancing crank for pumping units



pt. 3, 1940- A. M. BUTCHER 2,213,646

COUNTERBALANCING CRANK FQR PUMPING UNITS Filed June 11, 1938 2 Shuts-Sheet 1 66 m: 70 a? a? 7 22 32 v 'B ZZ/W a A'l'l'ONEY Sept. 3, 0- A. M. BUTCHER COUNTERBALANCING CRANK FQ'R .PUMPING UNITS Filed June 11, 1938 INVENTOR ATTORNEY 2 Sheets-Sheet 2 Patented Sept. 3,!940

UNITED STATES commence CRANK, FOB rumrmc umrs Antis M. Butcher, Tulsa, 13-, assignor to Happy Belting Company, Tulsa, Okla, a corporation of Oklahoma Application June 11,1938, sci-mm. 213,204

. 6 Claims. (01. 14491) This invention relates to a counterbalancing apparatus particularly employed in a .pumping unit to counterbalance or oifset weight of the pump rods, thereby reducing power consumption of the pumping unit and eliminating whipping tendency of the rods that ordinarily result in their rapid deterioration.

The principal object .of the invention is to provide a counterweight of this character that is adapted for adjustable mounting to compensate for change in load or adjustment in the eifective throw of the crank.

Other important objects of the invention are to provide a counterbalance structure that is adjustable by small increments thereby giving a desired counterweighting effect; to provide a counterbalance \that is adapted for support in a more effective position on the crank: to provide a counterbalance that facilitates attachment to the crank and which may be adjusted with safety on the part of the operator; to provide 'a counterbalance that has permanent ofl-center pivotal mounting to prevent accidental throw-01f of the counterbalancing elements; and to provide an attachment that eliminates shear of the attaching devices.

In accomplishing these and other objects of the invention, as hereinafter pointed out, I have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawings, wherein:

Fig. 1 is a perspective view of a well pumping unit equipped with a counterbalancing apparatus embodying the features of the present invention.

Fig. 2 is an enlarged section through the counterbalancing apparatus on the line 22 of Fig. 1 with the adjacent parts of the pumping unit shown in dotted lines.

Fig. 3 is an elevational view of the side of the counterbalancing apparatus nearest the pumping unit and showing the crank-shaft in section.

Fig. 4 is a detail perspective view of the apparatus showing one of the counterbalancing elements in removed spaced relation to better illustrate the structure.

Referring more in detail to the drawings:

I designates a conventional type of pumping unit which includes a base 2 carrying a Samsonpost structure 3 mounting a walln'ng beam 4 that oscillates about a shaft 5. Mounted on the base of the unit is a transmission indicated by the housing 6 which is actuated by a suitable prime mover (not shown) to rotate a crank-shaft I. Mounted on the projecting ends of the crankshaft 1 are crank-arms 8 having wrist pins 8 connecting pitmans ill with an equalizer bar ii that is pivotally mounted on the rear end of the walking beam.

The unit thus described is mounted adjacent the well so that the forward end I2 of the walking 5 beam projects over the wellhole to connect with the sucker rods I3 through a beam hanger l4.

When the unit is in operation the pump rods are reciprocated to lift fluid to the top of the well. Upon the upstroke the power must lift the 10 entire weight of the rods, plus the load of fluid in the well tubing, andon the following downstroke the rods drop with an abrupt jerk which places an undue strain upon the pumping unit and causes -a whipping action to occur in the 15 rods, with the result that excessive power is required and the equipment is rapidly deteriorated. To overcome these difliculties counterweights have been attached to the arms of the cranks to assist rotation on the upstroke of the rods, when the power is operating under iiiaximum load, and to control dropping of the rods on the downstroke. These counterweights are usually mounted for adjustment with respect to the axis of the crank so as to change the counterbalancing effect upon change in load or adjustment in throw of the crank to obtain a shorter or longer stroke. Since the .weight of the rods in deep wells is tremendous; the counterweights must be correspondingly heavy with the result that it is diflicult to securely anchor such heavy weights in adjusted position on the cranks. The extremely heavy weight of the counterbalances also renders adjustment diflicult and is hazardous to the operator making the adjustment. 7 As above pointed out, it is the object of the present invention to provide a counterweighting structure which is more efiective and overcomes these difficulties, as now to be described.

In the present invention the cranks 8 are of special design and each includes an arm portion l5 having a split hub or collar 16' that is secured to the crankshaft by a spline l1 and is rigidly clamped thereon by a bolt [8 extending through aligning ears I9 and 20 .on opposite sides of the 46 split portion of the collar, as clearly shown in Fig. 4. The arm I5 is of sufiicient length to give the desired maximum throw of the walking beam and is provided with a series of wrist pin-openings 2| so as to furnish a plurality of crank throws merely by changing the position of the wrist pin.

Extending laterally from the sides of the crank-arm, at a point substantially midway of the length thereof, are ears 22 and 23, having openings 24 and 25 to pass pivot pins 26 and 21 for front faces of the flanges 32 and 33. The flanges pivotally attaching counterbalancing elements 23 and 28, later described. Also projecting from the sides of the arm, in concentric relation with outer ends of the arms, as clearly shown in Fig. 4.

The counterweighting elements 26 and 29 are also best illustrated in Fig. 4 and each includes a substantially quadrant-shaped body 36 of sufficient size so that the combined weight of both elements is that require'djto effectively balance weight of the rods. The counterweights have thickness substantially conforming in thickness to the crank-arm and have flat side faces 31-48, bounded by radial ends 39-40,-and an arcuate outer face 4|. Formed at the juncture of the ends 39 and 40 is a recess; 42 of suflicient depth to accommodate the ears 22 and 23 so that the front face 3! lies substantially flush with the front face of the'crank. The recess, being only of the required depth to accommodate the ear, leaves suflicient metal to form a cooperating ear 43 having an opening 44 adapted to align with the opening 24 or 25, to pass the pivot pins 26 and 21 which are retained therein by cotter pins or the like 45 and 46 which extend through the projecting ends of the pins and engage washers 41, as best shown in Fig. 2. The rear faces of the counterweights have arcuate-shaped grooves 46 and 49 which are concentric with the respective pivot pins and of sufficient size so that the inner and outer arcuate edges 50 and 5| thereof slidably engage the inner and outer arcuatefaces 52 and 53 of the guides '30 and 3|; and are of a depth so that the bottom faces 54 engage the 32 and 33 have a series of regularly spaced apertures 55 and 56 and the bottoms. of the grooves In order to facilitate positioning 'of the coun-' terbalance weights in increments, selected adjacent openings .in the flanges 30 and 3| are connected by slots 6|-62 and 63-64 on the respective sides of the center line passing through the ears 22 and 23. In some instances it may be desirable to provide the counterweights just described with supplemental counterweights 65 that are arranged in series about the outer arcuate faces 4|. Therefore the arcuate faces of the counterbalances have flanges 66 of narrower width than' the body portions of the weights to fonn inset arcuate shoulders 69. These flanges have a series of apertures 16 which cooperate with similar apertures H in attaching flanges 12 of the supplemental weights, the flanges of the supplemental weights being of sufficient size to flt snugly within the shoulders 69, as best shown in Fig. 2. The supplemental weights are also of arcuate form and have inset shoulders 13 which engage the outer edges of the arcuate flanges and the ends thereof have projecting ribs 14 and 15 adapted to engage corresponding ribs on an adjacent supplemental weight. The supplemental weights are secured by fastening devices, such as bolts 16, thatpass through selected registering apertures.

To facilitate positioning and handling of the weights, they are preferably provided with open-. ings TI to pass a crowbar or similar tool. In order that the counterweights may have maximum movement about the arcuate guide portions of the cranks/the upper radial ends 33 thereof are recessed, as at 13 and 13, to accommodate the ends of the clamping bolt l6. The weights may be correspondingly extended at the opposite ends, as at 30 and 3|, so that they may overlap the ends of the crank, thereby providing a maximum amount of weight in metal.

. In adjusting a counterbalancing apparatus as counterbalancing efiect, the crank-arms are stopped on bottom dead center. The bolts attaching one of theweights, for example the weight 26, -are removed with exception of those in the upper portions of the slots 6| and 62 for that weight. The weight, however, will be retained by these bolts in its original position. Upon loosening the nuts of these bolts, the'clamping action is relieved and the counterbalance pivots on its pin 26 in sliding contact with the arcuate guide 36, a distance limited by the length of the slots. Another bolt will then be inserted in the upper ends of the slots to pass through registering openings in-the weights, 'and'tightened, whereupon the lower bolts will be removed leaving the upper bolts retaining the counterweights. Upon loosening these bolts the counterweight will again swing downwardly. It is thus apparent that the weight may be adjusted downwardly toward the outer end of the crank in increments governed by the length of the slots until it is in desired counterbalancing position. The other weight is then likewise adjusted.

To facilitate adjustment of the weights in the opposite direction, the cranks will be rotated until they are in top dead center position, whereupon the weights may be moved in increments in the manner above described closer to the axis of the crank-shaft. If additional counterweight is required, the supplemental weights 65 of required number may be applied to the peripheral flanges 66 and secured by attaching the bolts 16. After adjustment of the counterweights, bolts will be passed through all of the apertures in the respective weights to rigidly clamp the weights in their adjusted position.

Attention-is directed to the fact that when the weights are moved the maximum distance toward the shaft, the weight is substantially equally disposed about the shaft so that the counterbalancing effect is nil but when they are moved in the opposite direction the counterbalancing effect gradually increases to maximum.

From the foregoing it is obvious that I have provided a counterweight apparatus that is efficient in operation and which may be readily adjusted to give the desired counterbalance on the rods, thereby reducing the power consumption when the crank is moving in a direction to lift the rods and fluid in the well, and which will prevent whippingaction on downward movement of the rods since the counterbalance weights will tend to resist rotation of the crank under weight of the rods.

' What I claim and desire to secure by Letters Patent is:

1. A device of the character described including a crank, an arcuate guide projecting from one side of the crank with the axis of curvature spaced radially from the axis of crank rotation and having an arcuate series of spaced apertures, a counterweight having a series of correspondingly arranged apertures, means pivotally mounting the counterweight on the crank in the axis of said arcuate guide, certain of said apertures being connected to form a slot, fastening devices extending through the apertures in the counterweight and through selected apertures in the guide for clamping the counterweight in a selected position on the crank, and a similar fastening device extendable through the slot and a selected aperture to facilitate step by step adjustment of the counterweight on said guide.

2. A device of the character described including a crank, an arcuate guide projecting from one side of the crank and having a series of spaced apertures and an intermediate slot, a counterweight having a series of correspondingly spaced apertures, means pivotally mounting the counterweight on the crank in the axis of said arcuate guide, and fastening devices extending through the apertures in the counterweight and through selected apertures in the guide for clamping the counterweight in a selected position on the crank, with at least one of the fastening devices extending through the slot, whereby the counterweight is adapted for adjustment about said arcuate guide upon loosening of the fastening device extending through said slot when the other fastening devices are removed and a fastening device is alternately applied and removed in selected registering apertures with shift of said fastening device to the respective ends of the slot.

3. A device of the character described including a crank arm, an arcuate guide projecting from one side of the crank arm and having an arcuate rim provided with a series of spaced apertures, a counterweight having an arcuate groove to accommodate, said rim and provided with correspondingly spaced apertures, means pivotally connecting the counterweight with the crank arm in the axis of said guide, and fastening devices extending through the apertures in the counterweight and through selected apertures in the guide to retain said counterweight in a selected pivotal position.

4. A device of the character described including a crank, an arcuate guide having its ends connected with one side of the'crank and having an arcuate series of spaced apertures extending through said guide, an ear on said side of the crank having a pin opening in the axis of said guide, a counterweight having a portion engaged with said guide and provided with an arcuate series of correspondingly spaced apertures, a pin extending through the counterweight and through said ear opening for pivotally mounting the counterweight, and fastening devices extending through the apertures in the counterweight and through selected apertures in the guide to retain said counterweight in a selected pivotal position.

5. A counterbalancing crank including a central arm portion having a hub at one end and a wrist pin near the other end, ears on the respective sides of said arm portion and substantially equally spaced from a plane passing through the axis of said hub and wrist pin, arcuate wings on the respective sides of said arm portion and having ends connected, with the ends thereof whereby said arcuate wings are concentric with said ears, segmental weights pivotally connected with said ears and having arcuate grooves in the faces thereof for guidingly accommodating the arcuate wings, and fastening devices extending through said wings and through the segmental weights to clamp the segmental weights in selected adjusted positions relatively to said wings.

6. A device of the character described including a crank having an arcuate guide projecting from one side of the crank and ha g a series of spaced apertures, a. counterwei ht having a. series of correspondingly spaced ape tures, means pivotally mounting the counterweight on the crank in the axis of said arcuate guide, certain of said apertures being connected to form a slot, fastening devices extended through selected apertures in the guide and counterweight, and a fastening device extending through said slot and one of said apertures for facilitating s p by step adjustment of the counterweight on d guide.

ANTIS M. BUTCHER. 

